What sort of tank do you want - a single fish or a variety? Perhaps a biotope? South american vs. central american?
Also whats the dimensions of the tank at the edges, bowfronts have fairly narrow ends for their volume in my experience.
For a single fish I would say male salvini, love the shape of these 'mini-guapotes'. You could do a smaller centrepiece fish but have dithers eg. A less common Thorichthys eg. ellioti/"Blue Mixteco"/pasionis and have some swordtails and possibly a catfish for a mexican theme.
I would suggest a biotope amazon tank, but you dont like breeding pairs then lots of individual dwarf cichlids may look lost - but thats just my opinion. I'd do a school of corys, a single school of tetra and some dwarf cichlids eg. 1 german blue ram, 1 apistogramma cacatuoides and 1 keyhole cichlid. I'd probably do a larger cichlid to draw the focus such as a festivum - but choose tetras with care if you go down this route. Oh, and a plec of some description. With lots of sand, bogwood and plants.
If you wanted something unusual, a type of cichlid I've always liked is the pike cichlids. I'd either do a single 'belly crawler' or have a dwarf pike plus larger, more robust dithers eg. regani with deep bodied tetras.